Network communication systems often utilize network packets for communications within the network communication system. Timing information related to these network packet communications is often useful so that network nodes can synchronize their own operations, synchronize their operations with other network nodes, and/or determine relative time differences between internal or external events. Timing information can be obtained using a variety of techniques. For example, timing protocols can use GPS (Global Positioning System) or other GNSS (Global Navigation Satellite System) timing signals that are determined using GPS or GNSS receivers. Time code communication formats such as IRIG (inter-range instrumentation group) can also be used to transfer timing information with respect computing systems. Further, packet-based time synchronization techniques can also be used, such as for example, PTP (Precision Time Protocol), CES (Circuit Emulation Service), SAToP (Structure-agnostic Time-Division-Multiplexing over Packet), and/or other packet-based timing protocols.
Certain network-connected processing systems include multiple modular processing blades that are mounted in close proximity to each other as part of larger processing systems. Processing blades can be, for example, electronic components and processing devices that are assembled as a modular component on one or more printed circuit boards. These modular processing blades can then be stacked in close proximity to each other. With respect to timing information, the processing blades are typically configured to use locally generated timing sources, a master timing source distributed to the processing blades within a larger processing system, or a combination of master and local backup timing sources.
FIG. 1A (Prior Art) is a block diagram of an example embodiment for a network-connected processing system having a chassis 100 with processing blades 102, 112, and 122 that utilize local timing sources. As depicted, each individual processing blade 102, 112, and 122 includes an independent, local timing source 104, 114, and 124 as well as a local timing consumer 106, 116, and 126, respectively. The local timing sources 104, 114, and 124 can be, for example, a local clock generator, a local network packet-based timing module, and/or other local timing source. The timing consumers 106, 116, and 126 can be, for example, any logic circuitry or other electronic component resident on the blade that uses the timing information generated by its respective local timing source 104, 114, and 124. As such, each timing consumer 106, 116, and 126 on each blade 102, 112, and 122 consumes timing signals from its own local timing source 104, 114, and 124 for use in its operations.
FIG. 1B (Prior Art) is a block diagram of an example embodiment for a network-connected processing system having a chassis 100 with processing blades 102, 112, and 122 that receive a timing signal 156 from a master timing source 154. As depicted, the master timing source 154 is included on a master timing blade 152 that is also within the chassis 100. The master timing signal 156 is then distributed within chassis 100 to each of the blades 102, 112, and 122. The timing consumers 106, 116, and 126 for each of the blades 102, 112, and 122 consumes this master timing signal 156 for use in its operations. It is noted that the master timing signal 156 can be communicated within the chassis 100 to each blade 102, 112, and 122 through backplane connections and/or through other connections that are external to the blades 102, 112, and 122. Thus, in contrast to FIG. 1A (Prior Art), a centrally-generated master timing signal 156 is used by the consumers 106, 116, and 126 on the blades 102, 112, and 122.
FIG. 1C (Prior Art) is a block diagram of an example embodiment for a network-connected processing system having a chassis 100 with processing blades 102, 112, and 122 that receive a master timing signal 156 and have locally generated timing information that is used for backup timing. As with FIG. 1B (Prior Art), a timing signal 156 is generated by a master timing source 154 on a master timing blade 152, and this master timing signal 156 is distributed to the processing blades 102, 112, and 122 and is then consumed by timing consumers 106, 116, and 126. In addition, similar to FIG. 1A (Prior Art), each blade 102, 112, and 122 also has its own local backup timing source 104, 114, and 124, respectively. As such, each consumer 106, 116, and 126 on each blade 102, 112, and 122 also consumes timing signals from its own local timing source 104, 114, and 124 for use in its operations in addition to the master timing signal 156. For example, when the master timing signal 156 is not available due to clock failure or signal disruption, the timing consumers 106, 116, and 126 can use timing signals from their respective local timing sources 104, 114, and 123 as backup timing information.